Teaming up with contractor: their labor for some ROI on refi

[Lauren Williams]

Long story short... we cannot afford the full renovation cost of labor + material for a three family full renovation. Our contractor has offered to go in on the project with us. He proposed something along the lines that he would do the labor up front if we guaranteed a % return when we re-financed. We have no idea what a fair proposal would be. Does anyone have any experience in doing this or can offer a jumping off point to start the negotiation/contract? Thank you in advance!!